The converse, a company letting you go effective immediately, no severance, is sufficiently discourteous that it will likely prevent anyone from -wanting- to come back, as well as will build a reputation for them that will likely prevent a lot of talent from even looking at them as a possibility.
It behooves both employees and employers to keep their professional impressions positive.
When a typical employee's BATNA against informal blacklisting on the employer grapevine is minimum wage, homelessness or gun in mouth they have no expectation of control over the situation, even if they do nothing wrong. Whereas a company does expect to have control; all they have to do is not write down any discriminatory reasons, and just claim underperformance. So if they want you to dance like a bear, you'll either dance like a bear or start scrambling to fund your early retirement.
That's why we have nothing to say any time someone raises the question of how it's fair for things to be so asymmetrical: because it isn't fair, it's just what you have to do to make your monthly payments.
I think the main reason there's no notice by employers in the US is the lack of unions/organised labour to fight for rights like these.
Nobody ever talks about this side of the coin when it comes to layoffs and how companies behave. Everyone thinks oh its legal for them to just throw you out with no severance so its fine that they did that.
Then sadly anyone complaining about being laid off in that way is labeled a "bitter former employee", and quitting without giving 2 weeks notice is considered you slapping them in face.
But there is some law about notice. The WARN Act covers large employers who are conducting large layoffs. They have to give 60 days notice of large layoffs 50-500 depending on work site size and other factors.